The overall objective of the proposed research is to define possible controls for DNA biosynthesis during normal and neoplastic growth. i) We will continue to study the specific interaction(s) of two non-enzymatic proteins, C1 and C2, from HeLa cells with the homologous DNA polymerase alpha in DNA replication. The mechanism(s) of action of these proteins in promoting DNA replication of templates containing extended single-stranded regions will be defined. ii) Also, we will continue to investigate the interaction(s) of accessory proteins with DNA polymerase beta from HeLa cells. iii) We will complete the resolution of the components of a multi-enzyme complex for DNA biosynthesis that we have isolated from rat liver and HeLa cells. The physical and enzymic properties of the components will be completely characterized and their physiological interaction(s) defined.